Cysteine cathepsins and caspases are a class of cystein proteases which are associated with regulation of apoptosis, inflammation and cancer. Cysteine cathepsins and caspases are overexpressed in a variety of cancers. Downregulation and gene knockout studies in mice support a causal role for cysteine proteases in tumor growth, migration, invasion, angiogenesis and metastasis. Because of their broad pro-tumorigenic activities, these enzymes are considered viable targets for chemotherapy. However, cathepsins are necessary for normal cell function so selective inhibition within cancerous tissue would be beneficial to achieve high levels of therapeutic selectivity and to avoid systemic toxicity issues found with many cysteine cathepsin inhibitors.
Thus, compounds that enable the selective inhibition of cathepsins within cancerous tissue are needed. Delivery methods and techniques for enhancing or activating the selective inhibition of cathepsins are also needed.